A dual-wavelength anti-reflection coating and optical film thickness monitoring system for excimer laser

Abstract

The invention discloses a dual-wavelength anti-reflection film for excimer lasers and an optical film thickness monitoring system for preparing the anti-reflection film, so as to be applied to excimer laser instruments compatible with deep ultraviolet 193nm and 248nm. A dual-wavelength anti-reflection coating for excimer lasers, comprising a substrate and a multilayer film alternately formed of high-refractive-index films and low-refractive-index films arranged on the substrate in turn; the high-refractive index film is lanthanum fluoride, The low refractive index film is magnesium fluoride; the number of layers of the multilayer film is 4-10 layers. An optical film thickness monitoring system includes an electron beam evaporation source, a thermal resistance evaporation source, and a substrate to be plated. A baffle is arranged between the electron beam evaporation source, the thermal resistance evaporation source and the substrate to be plated. The dual-wavelength anti-reflection coating for deep ultraviolet excimer laser of the present invention not only has very low residual reflectivity of the substrate surface at the wavelengths of 193nm and 248nm, but also has the lowest absorption and scattering loss.

Description

technical field [0001] The invention relates to the field of deep ultraviolet excimer laser instruments, in particular to a dual-wavelength anti-reflection coating and an optical film thickness monitoring system for excimer lasers. Background technique [0002] Excimer laser is a kind of gas laser, its working gas is mainly composed of inert gas atoms argon (Ar), krypton (Kr), xenon (Xe) with very stable chemical properties under normal conditions and halogen atoms fluorine (F ), chlorine (Cl), bromine (Br), and iodine (I). Inert gas atoms generally do not form molecules with other atoms, but if they are mixed with halogen atoms and excited in the form of electric discharge, excited state molecules can be produced. When the excited state molecules transition back to the ground state, they are reduced to atoms again and emit photons, which are amplified by the resonant cavity and then emit laser light. Because the molecules in this excited state are fleeting and their lifet...

AI Technical Summary

Problems solved by technology

However, in this band, not only highly transparent substrate materials are very limited, but also applicable thin film materials are also very limited, especially high refractive index materials

What's more, even if there are only a few optional materials, since the photon energy is very close to the electronic bandgap of the material, it will produce high absorption, and the wavelength is very short, and the surface scattering is also very high. Therefore, the optical loss is very large, which not only causes the transmittance to be greatly reduced, but also causes the damage of the high-energy laser to the film. Because of this, reducing the optical loss of the film has become a difficult point in the design of deep ultraviolet excimer laser thin film devices. This is what the present invention is waiting for. Core issues to explore and solve

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